A payment terminal is used for electronic payments by card for effecting a transaction between a retailer or any other business person, the holder of the terminal, and a customer, the bearer of a payment medium, such as a bank card, with a memory or magnetic stripe, or a cheque, and which, in order to validate the transaction, can enter on the terminal a confidential code which is peculiar to it after the holder of the terminal has in particular entered the amount of the transaction. Such a terminal being considered as a slave, the transaction can then be transmitted to a master which retransmits it, over the switched telephone network STN or a dedicated network such as the TRANSPAC network, to a retailer processing centre RPC.
Payment terminals are already known, for example through the document U.S. Pat. No. 4,601,011, each having a module for entering data and a communication module, connected by cables to a central station and organized as a clustered system--the communication modules for all the terminals are connected to the central station by a single bus--or as a pooled system--the communication modules for the terminals are connected individually to the central station. These cable systems have the double disadvantage of comprising non-portable terminals, whose position is fixed, and having to lay cables, which is truly a disadvantage when such a cable system has to be installed in a place of sale which has already been fitted out or when the cash point has to be moved.
The need for having portable payment terminals is obvious for some business people who are anxious not to require their customers to move in order to enter their confidential code. Restaurant owners can be cited in particular. Considering only the latter it is eminently preferable for the restaurant waiters to present the terminal to a customer at the restaurant table rather than to ask him to go to the till.
Portable payment terminals are also known, having a module for entering data and in interface for communicating by means of infrared signals with a central station acting in fact as a functional pedestal or base for each terminal. Each terminal is powered independently by batteries and stores the transactions temporarily before transferring them to the storage memory in the base for subsequent transmission to an RPC centre. These terminals, admittedly mobile, nevertheless also have two drawbacks. Communication between them and their associated base, although effected by means of infrared signals, is enabled only if they are placed on the base, a prior condition for the initialization of the infrared transmission. From this drawback relating to the mechanical initialization stems the second, by which, since the terminals are isolated from their base during transactions, interrogation by them in order to request authorization for the transaction, for example, is impossible. The document EP-A-168 836 discloses a terminal of the latter type, but which is neither portable nor mobile. More precisely, the terminal in this document provides only some of the functions necessary for the transaction, the other functions being provided by the payment medium. The terminal in this document does not allow any use of bank cards on issue at present.